1. Field of the Invention
This invention relates to the field of electrical power generator sets (gensets), and more particularly to a method of wiring a small stand-by generator set (genset) to a residential home transfer switch.
2. Description of the Prior Art
A transfer switch is used to switch an electric load back and forth between a primary source, such as a utility, and a secondary source, such as a generator (genset). Transferring power from the primary source to the secondary source is necessary when the utility experiences a blackout. The transfer switch is also used to switch the power source back to utility power when the power outage is over.
If a modest size genset of 3-8 kW is connected to a residential house by means of a transfer switch at the distribution panel entrance, some method must be used to block the application of large loads that could overload the genset and cause the genset mounted circuit breaker to open. A genset of 5 kW can often power a typical profile of 110 V household loads, but cannot handle larger 220 V loads such as an electric stove, dryer, or central air conditioner.
Further, a three-wire 220 V service poses a problem unless a 220 V genset is used because typical distribution panels utilize two separate buses of 110 V power distributed to various loads. If a 110 V genset is used in association with such a three-wire 220 V service panel, then the distribution panel must be rewired so that all critical 110 V loads can be powered off one of the two buses; and then that bus must be attached to the load side of the transfer switch. The cost to connect a genset to an existing house is significantly less if the distribution panel does not have to be rewired, and if load management is not required.
Accordingly, it would be both beneficial and advantageous if a method could be provided to connect a 110 V genset to a transfer switch feeding a 220 V service entrance such that all 220 V loads are automatically blocked out and all 110 V circuits are accessed.